In recent years, with increasing global awareness of environmental issues as background, strengthening of exhaust gas regulations for diesel vehicles is progressing. Along with this, introduction of a DPF (Diesel Particulate Filter) system, a turbo system, a new engine system (common rail injection system), etc. is well underway in order to reduce PM (particulate matter), NOx, etc. in the exhaust gas, and the requirements for performance of air hoses for diesel vehicles, air hoses for automobiles such as DPF sensor hoses, etc. have also become stricter.
That is, in order to reduce PM or NOx in the exhaust gas, it is necessary to increase the combustion efficiency, and therefore, the DPF system, turbo system, etc. are required to be set at a high temperature, whereby air hoses for diesel vehicles, DPF sensor hoses, etc. are required to have heat resistance higher than ever before.
Also in gasoline vehicles, downsizing of the engine capacity has been advanced in order to improve the fuel economy, and a method for mounting a turbocharger system has been widely adopted in order to compensate for the engine output reduction. The fluid (air) to be directed from the turbo charger to an intercooler or an engine is at a high temperature and under a high pressure. Therefore, an air hose to transport such high-temperature high-pressure fluid is also required to have higher heat resistance.
As an air hose for a diesel vehicle having a heat resistance, a hose made of a laminate having an inner layer and an outer layer containing an ethylene acrylic rubber, a fluorinated rubber, etc., is disclosed, for example, in Patent Document 1.